Images are commonly obtained in the photographic art by a coupling reaction between the development product of a silver halide color developing agent, typically an oxidized aromatic primary amine developing agent, and a color forming compound commonly referred to as a coupler. The resulting image dyes are typically cyan, magenta and yellow dyes that are formed in or adjacent to silver halide layers sensitive to radiation complementary to the color of the radiation absorbed by the image dye.
Various ways are recognized in the photographic art for improving the quality of such images produced in color photographic silver halide materials. One of the ways has been to use a compound, especially a coupler, that is capable of releasing a diffusible development inhibitor moiety as a function of silver halide development. The patent and technical literature is replete with references to compounds, particularly couplers, generally referred to as DIR compounds, that can be used for improving graininess, sharpness and tonal rendition of images in such materials. Representative compounds are described in, for example, U.S. Pat. Nos. 3,227,554; 3,701,783; 3,615,506; 3,617,291; 3,379,529; 3,620,746; 3,384,657; 3,733,201; 4,248,962; 4,409,323 and 4,782,012.
A continuing need has existed for a development inhibitor moiety that enables increased inhibitor mobility that, in turn, provides useful interimage effects and increased sharpness of the color image produced in a color photographic silver halide material. It has been particularly desirable to provide such results with a releasable azole such as a triazole or tetrazole; or a benzotriazole, mercaptoazole, mercaptooxazole, or mercaptothiazole development inhibitor containing moiety. In this regard, it has been proposed to add an amide group to a mercaptoazole inhibitor moiety, such as described in European Patent Application 157,173 and Japanese Patent Application 60-184248. The amide function, such as acetamide, alone on a mercaptoazole inhibitor moiety was not found to provide the desired results as indicated by the comparative data in the following examples.
Releasable inhibitors of the art which are weakly adsorbed to silver and silver halide have been found to be most effective in improving sharpness of a color image because their effects are wider ranging. However, because of their weak inhibition of silver development, they must be coated in higher concentrations and so effects of seasoning of the developer occur. These may be overcome by making the inhibitors self-destructing upon prolonged exposure to the alkalinity of the developer solution. However coating large quantities of couplers releasing weak inhibitors can lead to other sensitometric problems. For instance, the dye formed as a consequence of inhibitor release may give sensitometric imbalance. These can be partially overcome by so-called "universal" couplers where the dye is unballasted and washes out or reacts to form colorless products, but these, in turn, lead to a loss of imaging efficiency usually seen as a loss of speed.
The effectiveness of a DIR coupler with respect to interimage effects can be evaluated by comparing the extent to which the released inhibitor causes the desired inhibiting effect on the adjacent layer ("Receiver") compared to the extent to which it causes an inhibiting effect on the layer in which it originates ("Causer"). Intralayer diffusion of an inhibitor precursor or inhibitor enables the inhibitor to cause an increase in sharpness of the image as well as a reduction in development in that layer.
A need has existed to provide a DIR compound, particularly a DIR coupler, in a photographic material and a process that enables formation of an image having improved sharpness with useful interimage results. Such a need has been especially important for a DIR compound, particularly a DIR coupler, that enables formation of a dye that is capable of being washed out of the photographic material upon processing. Moreover, such needs have existed with the added parameter that such a DIR compound must not require significantly modifying the development inhibitor moiety or the parent coupler moiety in a way that would adversely affect the desired properties of the inhibitor moiety, the stability, the reactivity toward oxidized developer, or other properties of the image dye-forming couplers present in the photographic material and process.